As detailed in U.S. Pat. No. 7,369,458, the entire teachings of which are incorporated herein by reference, sonar devices have widespread use in sport fishing, navigation, scuba diving, as well as any number of other recreational or commercial activities. A sonar system often includes a sonar unit and a transducer. The sonar unit includes a display for providing information to the operator. The transducer is often mounted under the waterline and is responsible for generating a sonic pulse (or sound pulse) and receiving echoes from objects in the water, from the bottom surface, or both.
The sonar unit often includes the electronic circuitry that produces a sonar pulse consisting of several cycles of a sonic signal at a fairly high output power. This pulse is delivered to the transducer usually via a shielded twisted pair cable. After transmission of the pulse, the transducer is typically used to “listen” for echoes. Received echoes produce very small signals, on the order of a few milli-volts, which are sent via a transmission line to a receiver circuitry in the sonar unit. In the sonar unit, the received echoes are amplified, filtered, and analyzed.